Species Composition and Ecological Characteristics of Native Seed Mixes in the Midwest (USA)

The midwestern United States has a well-developed native plant industry with a wide variety of native seed mixes available to buyers, often for the purpose of ecological restoration. Despite the influence of seed mixes on site-level restoration outcomes, there has yet to be a comprehensive overview of seed mixes available in the Midwest. We characterized seed mix composition by analyzing a database of 1,031 commercially available native seed mixes. Our objectives were: 1) to describe the major types of seed mixes; 2) compare basic ecological characteristics of the seed mix types, including species richness, relative weights of graminoids, species' wetland fidelities, and the blooming phenology of forbs; and 3) identify popular or "workhorse"species-species that are frequently and abundantly used in restorations. We identified six major types of seed mixes reflecting different habitat targets and soil moisture conditions: pollinator habitat, tallgrass prairie, wetland, wet prairie, dry prairie, and woodland/savanna mixes. Species richness was generally greatest for wetland mixes, whereas tallgrass prairie mixes were the most species-poor. Percent of seed mix weight which was graminoids was highest in tallgrass prairie mixes, whereas it was low in pollinator habitat mixes. The species composition of the mixes reflected a moisture gradient in the field from wetlands to dry prairies. Despite their infrequency, woodland/savanna mixes were distinct because they had many unique species, and the blooming phenology was markedly different due to the presence of earlier-flowering forbs. Popular species in midwestern seed mixes were generalist prairie species with inexpensive seed, including dominant C4 grasses and early successional, showy forbs. This study is a descriptive overview of the current state of native seed mixes in the Midwest and suggests that most mixes consist of standard components of target communities.